In order to ensure reliable radio communication between terrestrial locations, it is important to have a reliable method of estimating the extent to which the radio signals attenuate (i.e., to estimate the path loss) as the signal propagates between the locations. Radio signal propagation in free space is affected by a variety of phenomena including diffraction, refraction, reflection, absorption by the atmosphere, and obstruction by material and by the earth's horizon. The radio link budget which takes into account all the gains and losses from the transmitter, through the medium, to the receiver depends on a variety of factors including antenna properties (gain, directivity, front-to-back ratio, etc.), frequency or wavelength of the radio signal, interferers, natural and man-made obstructions, environmental factors such as altitude and weather, link distance, and antenna height, among other factors. Generally, the more the path between the transmitter and the receiver antennas is clear from obstructions, the less the signal losses. One way to ensure that the path is free of obstructions is to raise the height of the transmit and/or receive antennas above any obstructions that might exist along the path ensuring sufficient clearance within the first Fresnel zone. However, raising antenna heights come with additional costs including equipment costs, constructions costs, costs to obtain the relevant permits and approvals, and maintenance costs. As such, when designing radio links it is beneficial to design radio antenna towers so that they are as tall as they need to be for reliable, high throughput and low latency links, but are no taller. To assist in designing radio links, wireless engineers typically utilize a radio path design tool in the design process. A radio path design tools allows the wireless engineer to model the radio path between two proposed locations for radio antenna towers.
One of the limitations in existing radio path design tools is that the tool computations are based on pre-determined latitude and longitude coordinates for transmitting and receiving antenna towers. Any latitudinal or longitudinal deviation to the placement of either antenna after the radio link is designed affects the computed radio propagation parameters and may thereby result in unreliable radio links. In actual deployment scenarios, it is not uncommon that the radio link deployment team might prefer to change the placement of antenna towers away from where the initial site analysis team envisioned their placement. For example, the deployment team might realize that moving an antenna tower a certain distance away from the originally identified site may result in tower construction economies, for example, by reducing tower height when erected on an adjacent hill or other elevated topography, or by avoiding other construction hazards in chosen site. Unfortunately, existing tools provide little flexibility in antenna tower placement from the beginning of the design phase. FIG. 1, for example, depicts a point-to-point path profile 50 generated by an example of a currently-available radio frequency signal propagation and signal loss design tool. The path profile 50 depicts the placement of a first tower 55 at one margin of the interface and a second tower 60 at the other margin of the interface. In between the two towers, the path profile 50 depicts intervening terrain 67, the Earth's curvature contour 65, and the path link 70. By only considering the terrain and Earth's curvature contour between the first tower 55 and second tower 60, the prior art design tool fails to provide much design flexibility for wireless engineers designing radio links. For example, the radio link designer is unable to readily ascertain that the antenna towers are on optimal sites just by looking at the path profile 50. It could be that the current proposed location for one of both of the antenna towers is on a hill slope such that, by relocating the antenna(s) to the top of the hill, much shorter antenna towers would need to be erected to yield a line-of-sight path without substantially affecting link budget when the path link 70 distance increases. Additionally, it could turn out that the proposed site for locating the first tower 55 or the second tower 60 proves infeasible during site construction. In this case, wireless engineers using prior art design tools would have to repeat the path link design after extending the path link 70 in order to verify that new tower sites also meet the target link budget—for example, to verify that the line-of-sight path 75, first Fresnel zone line 77, or 60% of first Fresnel zone line 76 is still clear of obstructions after extending the path link 70 beyond what is currently depicted in path profile 50. Such prior art radio path design tools often result in the selection of suboptimal sites for antenna deployment, or cause an undue amount of effort to be undertaken by engineers in order to arrive at satisfactory sites.